Study of Microstructural Effect in Particulate Composites

2002 ◽  
Author(s):  
Y. W. Kwon ◽  
C. T. Liu
Keyword(s):  
Particle Distribution ◽  
Tensile Specimen ◽  
Particulate Composites ◽  
Critical Crack ◽  
Continuous Growth ◽  
Damage Initiation ◽  
Short Cracks ◽  
Multi Scale ◽  
Constituent Material ◽  
Random Particle

The effects of random and non-uniform particle distribution on the damage initiation and growth leading to a crack were investigated for particulate composites using a multi-scale technique. Damage was described at the constituent material level (i.e. micro-level) and the results compared well qualitatively and quantitatively with experimental observation. Non-uniform, random particle distribution yielded sporadic crack initiation and growth within a uniform tensile specimen. No local crack propagated beyond a certain size. Breakage of the specimens was not caused by the continuous growth of a single critical crack. Instead, coalescence of neighboring sporadic short cracks resulted in breakage of the specimens. Computer simulation indicated that random particle distribution affected the strength of the composite significantly, but as expected, not its effective stiffness.

Microstructural Effects on Damage Behaviour in Particle Reinforced Composites

2003 ◽  
Vol 11 (1) ◽  
pp. 1-8
Author(s):  
Y. W. Kwon ◽  
C. T. Liu
Keyword(s):  
Particle Distribution ◽  
Tensile Specimen ◽  
Initial Crack ◽  
Critical Crack ◽  
Continuous Growth ◽  
Damage Initiation ◽  
Short Cracks ◽  
Constituent Material ◽  
Microstructural Effects ◽  
Random Particle

This paper discusses the effects of non-uniform, random particle distribution on damage initiation and growth, leading to short cracks and breakage of particle reinforced composite specimens. A multi-scale technique was employed to model and simulate damage. Damage was described at the constituent material level (i.e. micro-level) and the results were compared qualitatively and quantitatively with experimental observation. Both results agreed well. Non-uniform, random particle distribution yielded sporadic crack initiation and growth within a uniform tensile specimen. No local crack propagated beyond a certain size. Breakage of the specimens was not caused by the continuous growth of a single critical crack. Instead, coalescence of neighbouring sporadic short cracks resulted in breakage of the specimens. Computer simulation indicated that random particle distribution affected the strength of the composite significantly, but as expected, not its effective stiffness. However, if there was a pre-existing crack in the specimen before loading, the effect of the random particle distribution on the initial crack and the strength of the composite was almost negligible.

Multi-Scale Approach for Nonhomogeneous Microstructural Effects on Damage in Particulate Composites

2003 ◽  
Author(s):  
W. M. Cho ◽  
Y. W. Kwon ◽  
C. T. Liu
Keyword(s):  
Volume Fraction ◽  
Global Analysis ◽  
Particle Volume Fraction ◽  
Crack Tip ◽  
Particulate Composites ◽  
Local Analysis ◽  
Particle Volume ◽  
Damage Initiation ◽  
Volume Fractions ◽  
Multi Scale

This study investigated the effects of random and non-uniform particle distributions on the damage initiation and growth in particulate composites. Numerical specimens with either no crack or an existing crack were examined. For the cases with no crack, the effect of sizes of the representative area for non-uniform particle volume fractions was studied on the overall stress-strain curves and the results were compared with that of the specimen with uniform particle volume fractions. Other studies considered cracked specimens, either single edge crack or a center crack. The global-local approach was used along with multi-scale technique. The global analysis determined the deformations around the crack tip. Then, the local analysis evaluated the damage progress at the crack tip using the solution of the global analysis as boundary conditions. The results showed non-uniformed particle volume fractions in particulate composites caused the crack growth at lower applied loads than the uniform particle volume fraction. Statistical data were also plotted for the non-uniform particle volume fraction cases.

Crack Growth Resistance of Ceramic Matrix Composites and Anisotropic Stiffness Prediction/Measurement

2018 ◽  
Author(s):  
Cody Godines ◽  
Saber DorMohammadi ◽  
Jalees Ahmad ◽  
Rabih Mansour ◽  
Gregory N. Morscher ◽  
...  
Keyword(s):  
Crack Growth ◽  
Mixed Mode ◽  
Elevated Temperatures ◽  
Ceramic Matrix ◽  
Crack Growth Resistance ◽  
Oxide Ceramic ◽  
Damage Initiation ◽  
Multi Scale ◽  
Failure Evolution ◽  
Anisotropic Stiffness

A Durability and Damage Tolerance (D&DT) analysis of an S200 Nicalon/SiNC and Oxide/Oxide Ceramic Matrix Composite (CMC) was conducted to determine the crack growth resistance (GIc) of Wedge Loaded DCB (WDCB) at Room and Elevated temperatures (RT/ET) and compared with experimental tests observations. Wedge Loading gives proper crack path without mixed mode effects and can be used at high temperature in a furnace. Load displacement, GIc, electrical resistivity and acoustic emission was measured by tests and compared to FE based Multi Scale Progressive Failure Analysis (PFA) of the WDCB specimen. The critical damage events studied included damage initiation, damage propagation, fracture initiation, and fracture propagation as the components were being loaded. Effect of defects on Modulus (E11, E22, and E33) was conducted by Electrical Resistance (ER) Measurement at Room temperature (RT). Multi-Scale modeling simulation considered de-homogenized nano-assisted micromechanics analytical formulation, a Mori Tanaka based stiffness correction including void shape, size, distribution and orientation effects. Emitted/received signal amplitude by ER Vs. time was used to evaluate reduction of stiffness in all directions resulting in anisotropic stiffness of As-Built specimens. WDCB specimen was tested to failure at RT/ET to produce reliable GIc values with minimum specimen size. Many parameters that contribute to specimen failure included interface coating thickness, mixed mode failure evolution, interlaminar defects, delamination damage, crack bridging, and fiber fracture which were all studied in detail in this work. All simulations correlated well with test.

Multiscale Modelling of Non-Crimp Fabric Composites

2012 ◽  
Author(s):  
L. E. Asp ◽  
E. Marklund ◽  
J. Varna ◽  
R. Olsson
Keyword(s):  
Performance Prediction ◽  
Textile Composites ◽  
Point Of View ◽  
Damage Initiation ◽  
Multi Scale ◽  
Transverse Tensile ◽  
Fabric Composites ◽  
Final Failure ◽  
Plane Transverse ◽  
Scale Modelling

Damage initiation and evolution in NCF composites leading to final failure includes a multitude of mechanisms and phenomena on several length scales. From an engineering point-of-view a computational scheme where all mechanisms would be explicitly addressed is too complex and time consuming. Hence, methods for macroscopic performance prediction of NCF composites, with limited input regarding micro- and mesoscale details, are requested. In this paper, multi-scale modelling approaches for in-plane transverse strength of NCF composites are outlined and discussed. In addition a simplistic method to predict transverse tensile and compressive strength for textile composites featuring low or no fibre waviness is presented.

3D Micro-Structural Modeling of Vibration Characteristics of Smart Particle-Reinforced Metal-Matrix Composite Beams

2019 ◽  
Vol 19 (07) ◽  
pp. 1950078
Author(s):  
Recep Ekici ◽  
Vahdet Mesut Abaci ◽  
J. N. Reddy
Keyword(s):  
Particle Size ◽  
Metal Matrix Composite ◽  
Metal Matrix ◽  
Vibration Amplitude ◽  
Natural Frequencies ◽  
Particle Distribution ◽  
Volume Fraction ◽  
Particle Volume Fraction ◽  
Particle Volume ◽  
Random Particle

In this study, the effects of micro-structural parameters such as particle volume fraction, size and random distribution of Al 6061/SiC particulate metal-matrix composite (MMC) beams on free vibration response and the active vibration control are investigated. For this purpose, numerical particle-reinforced MMC (PRMMC) beam specimens were modeled with 3D finite elements, and the cubic-shaped reinforcing SiC particles were randomly distributed in Al 6061 metal matrix similar to an actual micro-structure. The particle size and especially volume fraction play an important role on the natural frequencies of the smart PRMMCs although they have no effect on the mode shapes. The random particle distribution has minor effect on the natural frequencies of the smart PRMMCs. With the increase of the feedback control gain, both the vibration amplitude and the suppression time are reduced reasonably. Increasing the particle volume fraction induces an important reduction in the damping time and the vibration amplitude for both the controlled and uncontrolled damped vibrations. Finally, increasing the particle size decreases the vibration suppression capacity and increases the vibration amplitude and time slightly. Random particle distribution had no obvious effect on the uncontrolled and controlled vibrations.

scholarly journals High-resolution stereolithography using a static liquid constrained interface

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Aftab A. Bhanvadia ◽  
Richard T. Farley ◽  
Youngwook Noh ◽  
Toshikazu Nishida
Keyword(s):  
Immiscible Liquid ◽  
Process Conditions ◽  
Layer By Layer ◽  
Continuous Growth ◽  
Multi Scale ◽  
Aspect Ratios ◽  
Growth Modes ◽  
Wide Range ◽  
Process Reliability ◽  
Micrometer Scale

Abstract3D printing using conventional stereolithography is challenging because the polymerized layers adhere to the solid constraining interface. The mechanical separation forces lead to poor process reliability and limit the geometrical design space of the printed parts. Here, these challenges are overcome by utilizing a static inert immiscible liquid below the resin as the constraining interface. We elucidate the mechanisms that enable the static liquid to mitigate stiction in both discrete layer-by-layer and continuous layerless growth modes. The inert liquid functions as a dewetting interface during the discrete growth and as a carrier of oxygen to inhibit polymerization during the continuous growth. This method enables a wide range of process conditions, such as exposure and resin properties, which facilitates micrometer scale resolutions and dimensional accuracies above 95%. We demonstrate multi-scale microstructures with feature sizes ranging from 16 μm to thousands of micrometers and functional devices with aspect ratios greater than 50:1 without using sacrificial supports. This process can enable additive 3D microfabrication of functional devices for a variety of applications.

Wave dispersion characteristics of agglomerated multi-scale hybrid nanocomposite beams

2019 ◽  
Vol 54 (4) ◽  
pp. 276-289 ◽  
Author(s):  
Farzad Ebrahimi ◽  
Ali Seyfi ◽  
Ali Dabbagh
Keyword(s):  
Beam Theory ◽  
Wave Dispersion ◽  
Wave Frequency ◽  
Equivalent Material ◽  
Hybrid Nanocomposite ◽  
Governing Equations ◽  
Mechanical Responses ◽  
Multi Scale ◽  
Constituent Material ◽  
Kinetic Relations

Herein, the agglomeration effect of nanoparticles on the wave dispersion of multi-scale hybrid nanocomposite beams is investigated. The constituent material consists of both macro- and nano-reinforcements which are dispersed in the polymer matrix. Homogenization is conducted according to the well-known micromechanical methods. Herein, the combination of the Eshelby–Mori–Tanaka model and the rule of the mixture is implemented in order to estimate the equivalent material properties of the nanocomposite beam. Also, a refined higher-order beam theory is used in order to calculate the kinetic relations free from utilizing an additional factor to account for the shear deformation. Furthermore, the governing equations are achieved by applying Hamilton’s principle. Then, the governing equations are solved analytically to enrich the wave frequency. The effects of various parameters on the variation in wave frequency and phase velocity of the multi-scale hybrid nanocomposite beam are studied. The results of this study reveal that the mechanical responses of the system decrease whenever the nanotubes are inside the clusters.

Numerical Study of Damage Growth in Particulate Composites

1999 ◽  
Vol 121 (4) ◽  
pp. 476-482 ◽  
Author(s):  
Y. W. Kwon ◽  
C. T. Liu
Keyword(s):  
Cell Model ◽  
Numerical Study ◽  
Matrix Material ◽  
Three Dimensional ◽  
Crack Tip ◽  
Particulate Composite ◽  
Crack Size ◽  
Particulate Composites ◽  
Specimen Thickness ◽  
Damage Initiation

A numerical study was conducted to simulate and predict damage initiation and growth around the crack tip crack tip in particulate composite specimens made of hard particles embedded in a soft rubber-like matrix material. Therefore, damage evolution in the matrix material around crack tips was investigated. The progressive damage was modeled using a micro/macro-approach which combined two levels of analyses like the micro-level and the macro-level analyses. Damage description was undertaken at the microlevel using a simplified three-dimensional unit-cell model and an isotropic continuum damage theory. The numerical study examined both him and thick specimens with a short or long edge crack to understand the effects of specimen thickness and crack size on the damage initiation, growth, and saturation. Numerical results were compared with experimental data.

Sign in / Sign up

Export Citation Format

Share Document